What's to technically stop you using a phone contract in a tablet like this? For example the '3' £13 monthly sim has minutes texts and unlimited Internet. As long as you use the correct APNs, how would Three tell that your android tablet isn't an android phone (other than not using your minutes and texts every month)?

GiffGaff do 500MB for £5 a month or 1GB for £7.50
Three do 1GB for £7.50 on a rolling monthly contract
Ovivo do 500MB per month for "free" but with pushed adverts

Any other deals out there?

One of the best "deals" at present seems to be various eBay sellers who are selling 3Gb/3 month 3 PAYG broadband SIMs for just over £11 (for the cheapest). While these COULD, in theory, be topped up at the end of 3-months it would be cheaper to buy another at that point and start again!

What's to technically stop you using a phone contract in a tablet like this? For example the '3' £13 monthly sim has minutes texts and unlimited Internet. As long as you use the correct APNs, how would Three tell that your android tablet isn't an android phone (other than not using your minutes and texts every month)?

They can often tell by analysis (of packet headers, browser IDs etc.) - but if all were Android devices it might be MUCH harder.

Many people seem to ignore the "no tethering" rules but many ISPs also seem to not bother too much unless the data usage gets very high! A colleague of mine has no landline phone and does all her web-access from home via her "unlimited data" mobile contract - and that INCLUDES laptop tethered access! if she ever starts streaming much video, for example, they are very likely to spot her then!

3 seem NOT to be one of the more proactive in policing their SIM cards.

One of the best "deals" at present seems to be various eBay sellers who are selling 3Gb/3 month 3 PAYG broadband SIMs for just over £11 (for the cheapest). While these COULD, in theory, be topped up at the end of 3-months it would be cheaper to buy another at that point and start again!